Field of the Invention
The present invention relates to a machine tool system that opens and closes a door to exchange a work of a machine tool.
Description of the Related Art
It is demanded to automate manufacturing at a higher speed to manufacture products at lower cost. There is a processing automation system that uses a machine tool to meet this demand. This automation system not only automatically processes a work but also exchanges the work (attaches an unprocessed work and delivers a processed work). The work is exchanged by a work exchange device. Further, it is necessary to perform an operation of covering a machine tool with a cover and closing a door to prevent scattering of chips and a cutting fluid, and opening the door to enable movement of the work exchange device to an inside of the cover during exchange of a work, and the door is also automatically opened and closed. Although there is a case where a fluid pressure cylinder that uses a hydraulic pressure and air is used to open and close the door, it is difficult to control a position and a speed, and therefore it is difficult to lower a speed immediately before a door stop position and accurately stop the door at an arbitrary position.
Japanese Patent No. 4629392 discloses opening and closing a door at a high speed by using a servo motor and a ball screw. This is because it is possible to decelerate the door with the servo motor near an opening/closing end even when the door is moved at a high speed, and stop the door at the arbitrary position. Consequently, it is possible to reduce a shock at the opening/closing end and accelerate a speed to open and close the door by opening the door only by a necessary width. Consequently, it is possible to reduce a time taken to open and close the door, and reduce a cycle time.
Further, Japanese Laid-Open Patent Publication No. 2010-228063 (hereinafter referred to as “JP2010-228063A”) relates to a door that is provided between a processing area (machining area) inside a machine tool and a standby area of a tool, but not a door (opening/closing door) that partitions an interior and an exterior of the machine tool. The invention therein reduces a processing time by eliminating a waste of an opening/closing time of the opening/closing door during exchange of the tool by changing a width by which the door is opened.